ABSTRACT
Natural weathering degradation of the blends of recycled polypropylene (PPr) with
Polystyrene (PS), Polyvinyl chloride (PVC) and Virgin Polypropylene (PPv) was
studied. Film samples of 25 by 1.5 by 0.02Cm3.PS, PVC and PPv were blended with
PPr for the purpose of improving its mechanical properties, which was generally
considered as inferior. While no particular blends had over all good result of all the
mechanical Properties tested, however, PS/PPr produced the best result of tensile
strength, followed by the blends of PPv/PPr and PVC/PPr. The blend of PPv/PPr had
the highest elongation followed by the blends of PVC and PS. The young modulus
results show that at 20%, the PS blends has the highest young modulus. Also PS blend
resist embrittlement more than PPv and PVC blends. In summary the blends of PS and
PPr at ratio 20:80 is considered good enough to improve the mechanical properties of
recycled polypropylene better than the other blends.
TABLE OF CONTENTS
TITLE PAGE I
DECLARATION II
CERTIFICATION III
DEDICATION IV
ACKNOWLEDGEMENT V
ABSTRACT VI
TABLE OF CONTENTS VII
LIST OF TABLES X
LIST OF SCHEMES XI
LIST OF PLATES XII
LIST OF FIGURES XII
CHAPTER ONE
INTRODUCTION
1.1 Introduction 1
1.2 Aim of the research 3
CHAPTER TWO
LITERATURE REVIEW
2.1 Polypropylene; a brief history 4
2.2 Polystyrene; a brief history 6
2.2.1 Structure of Polystyrene 6
2.2.2 Polymerisation of Polystyrene 7
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2.3 polyvinyl chloride; a brief history 7
2.3.1 Polymerisation 9
2.4 Polymer weathering 9
2.41 Mechanical properties of polymer 10
2.4.2 Polymer blending 11
2.4.3 Process of u.v degradation in polymers 12
2.4.4 Chain Scission and Cross linking 13
2.4.5 Molecular Mass Reduction 13
2.4.6 Photo oxidation; a free radical chain mechanism 14
2.4.7 Photodegradation Chemical reaction process in polypropylene 15
CHAPTER THREE
MATERIALS AND METHODS
3.1 Introduction 18
3.2 Material acquisition and preparation 18
3.2.1 Materials and Methods 18
3.2.2 Preparation 18
3.3 Formulations 19
3.4 Productions of films 21
3.4.1 Environmental Exposure 22
3.4.2 Method of Monitoring Degradation 23
3.4.3 Embrittlement Time 23
3.4.4 Tensile tests 24
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CHAPTER FOUR
RESULTS AND DISCUSSION
4.1 Tensile strength 25
4.2 Breaking elongation 33
4.3 Young modulus 40
4.4 Embrittlement 47
CHAPTER FIVE
SUMMARY AND CONCLUSION
5.1 Summary and conclusion 50
REFERENCES 51
APPENDIX 53
CHAPTER ONE
1.1 INTRODUCTION
Plastics; materials made up of large organic (carbon – containing) molecules that
can be formed into a variety of products. The molecules that compose of plastics
are long carbon chain that gives plastics many of their useful properties. In
general, material that is made up of long chain like molecules are called
polymer.
Plastics are indispensable to our modern way of life. Plastics are used in
low performance products like toys, wrapping product, storage of beverages and
also high performance products like automobile, aerospace, constructions,
packaging and electrical industries. Plastics are also used in specialized fluids,
such as the health industries to make medical instruments, dental fillers, optical
lenses and bio compatible joints.
Plastic materials have substituted ferrous, wood and ceramic materials in many
applications, for this reason, plastic consumptions have increased exponentially
in the past decade. Infact, the demand for plastic products and goods is on the
increase due to rapid population growth and changes in consumption pattern,
particularly for packaging; shopping, carrier bags, containers, agricultural tools,
water satchet and house hold items.
There are environmental problems and challenges associated with the
management of plastic wastes in Nigeria as well as in many developing
countries. Due to their non – biodegradability and diverse applications, plastic
wastes from petrochemical source are prevalent in the environmental and causes
health hazards.
2
Chocking of fertile soils, flooding due to blockage of drainage, breeding
grounds for mosquitoes, death of livestock due to ingestions, food hazards,
pollution (dioxin and furan) from burning of plastics. According to the study
carried out by the federal ministry of environment, Nigeria generated more than
2.260 million tonnes of plastic wastes annually. Anonymous. (2008)
The Government through the Federal Ministry of Land, Housing and
Urban Development has embarked on a number of measures to address these
problems being encountered in the management of plastic wastes in Nigeria.
These measures include the introduction of an integrated waste management
scheme for Nigerian cities under a public – Private partnership (PPP)
arrangement in which the recovery, recycling and re-use of plastic waste is a
major component. Anonymous (2008)
The efforts of the Government are also being complemented by private
sector operators who engage in collection and recovery of plastic wastes which
are then sorted, shredded, blended and reprocessed to make new products or sent
to secondary processing plants to make “ lower” quality products.
Although scientifically, it has been proved that recycled process affects
the properties of plastics, these changes have not been qualified. This study will
be directed towards quantifying the property changes in recycled polypropylene
and to improve on these properties when it is blended with virgin polypropylene,
polystyrene and polyvinyl chloride
3
1.2 AIM OF THE RESEARCH
This research is concerned with the effect of weathering on mechanical
reliability of plastic products. Under outdoor conditions, polymer degrades,
mainly due to action of UV- light, while heat and humidity have secondary
effects. Degradation tends to reduce the mechanical reliability, and in some
cases this reduction may be very drastic.
The ultimate aim of this research is to;
1. Investigate the mechanical properties of recycled polypropylene.
2. Established the level of degradation on the mechanical properties of
recycled polypropylene.
3 Deduce how the properties can be improved upon when blended with
another polymer.
4 Encourage the use of recycled polypropylene for new product, hence
reduce environmental pollution.
5 Formulate new materials with peculiar properties than the existing ones.
4
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